Runtime

[Richard West]

Hi everyone,

I am using the Runtime class to run a java program by using the java intreperter.

This is what i am doing to get the output stream of the java program

String str18 = //The string to run the java program with the java intreperter
String str20 = null;
 
Runtime Runtime1 = Runtime.getRuntime();
Process Process1 = Runtime1.exec(str18);
 
//This is the line where i am trying to get the output stream of the java 
//program by getting its inputstream. I am right am i not or do i have
//to get its outputstream of the program instead
 
BufferedReader in = new BufferedReader(new InputStreamReader(Process1.getInputStream()));
 
while ((str20 = in.readLine()) != null)
{ 
System.out.println(str20);   
}
 
Process1.waitFor();

Now this is the java program i am running

 
public class JTest
{
public static void main(String args[])
{
int i = 0;
 
for(i=0;i<5;i++)
{
System.out.println("This is ouput " + i);
}
 
}
}

The thing is the java program runs and everything is alright but i am not getting its console output by the way i am doing it.

I am right in that to get the output of a program, i get its inputstream and not outputstream right?

I am also using threads to run the program but that should have no effect right?

If what i am doing is wrong could someone guide me on the right way to get the output stream of a program

Any help is greatly appreciated

Thank You

Yours Sincerely

Richard West

[Jean-Sebastien Abella]

believe it or not I get the output!

[Richard West]

Hi everyone,

Jean, i am listing a Runs class and a sample swing program so you can compile them and see what i mean first hand.

i tried running the above JTest program of mine with the below Runs class and it works but now here comes the weird part, it does not work with a swing application as i will list.

You see the runtime in my program does not seem to be able to get any output streams from the swing program

This is what i am doing to run the swing application

public class Runs
{
 
public void runswing(String Str18)
//Str18 is the string to run the java program with the java intreperter
 
String str20 = null;
String str21 = null;
 
Runtime Runtime1 = Runtime.getRuntime();
Process Process1 = Runtime1.exec(str18);
 
//This is the line where i am trying to get the output stream of the java 
//program by getting its inputstream. I am right am i not or do i have
//to get its outputstream of the program instead
 
BufferedReader in1 = new BufferedReader(new InputStreamReader(Process1.getInputStream()));
 
while ((str20 = in1.readLine()) != null)
{ 
System.out.println(str20);   
}
 
BufferedReader in2 = new BufferedReader(new InputStreamReader(Process1.geterrorStream()));
 
while ((str21 = in2.readLine()) != null)
{ 
System.out.println(str21);   
}
 
Process1.waitFor();
}
 
public static void main(String args[])
{
Runs a = new Runs();
a.runswing(//The string to run the java program with the java intreperter);
}                                         
}

now this is the simple swing program is running

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
 
public class JButtons implements ActionListener
 
{
 
JFrame fr = new JFrame ("Frame");
JLabel Label1 = new JLabel("Label1                       ",SwingConstants.RIGHT);
JButton Button1 = new JButton("Button 1");
JButton Button2 = new JButton("Button 2");
 
public void initialize ()
{ 
Container pane = fr.getContentPane();
pane.setLayout(new FlowLayout());
fr.setSize(250,300);
fr.setLocation(300,300);
fr.setBackground(Color.lightGray);
pane.add(Label1);
 
pane.add(Button1);
pane.add(Button2);
 
fr.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Button1.addActionListener(this);
Button2.addActionListener(this);
fr.pack();
fr.setVisible(true);
}
 
public void actionPerformed(ActionEvent event)
{
JComponent b = (JComponent)event.getSource();
 
if(b == Button1)
{
Label1.setText("Button 1 clicked");
System.out.println("You clicked Button 1");
}
 
else if(b == Button2)
{
Label1.setText("Button 2 clicked");
System.out.println("You clicked Button 2");
}
 
}   
public static void main(String args[])
{
JButtons a = new JButtons(); 
a.initialize();
}
} 

Now the problem is that when i run the above swing program using my Runs class(listed above) and click on their JButtons the console is supposed to output the corresponding JButton that is clicked.

Now i am still not able to read the console output. I have a feeling that the problem has to do with the while loops in the Runs class i have above but i am not sure and i can't prove it.

Am i missing something or am i doing something wrongly?

I hope someone can guide me how to do this correctly

Any help is greatly appreciated

Thank You

Yours Sincerely

Richard West

[Jean-Sebastien Abella]

i can assure that i get the output either from the first Test class or the second JButtons one..

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class test {
public static void main(String[] args) {


String str18 = "java JButtons";
String str20 = null;

Runtime Runtime1 = Runtime.getRuntime();

try {
Process Process1;
Process1 = Runtime1.exec(str18);


//This is the line where i am trying to get the output stream of the java
//program by getting its inputstream. I am right am i not or do i have
//to get its outputstream of the program instead

BufferedReader in = new BufferedReader(new InputStreamReader(Process1.getInputStream()));

while ((str20 = in.readLine()) != null)
{
System.out.println(str20);
}

Process1.waitFor();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

and
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class JButtons implements ActionListener

{

JFrame fr = new JFrame ("Frame");
JLabel Label1 = new JLabel("Label1 ",SwingConstants.RIGHT);
JButton Button1 = new JButton("Button 1");
JButton Button2 = new JButton("Button 2");

public void initialize ()
{
Container pane = fr.getContentPane();
pane.setLayout(new FlowLayout());
fr.setSize(250,300);
fr.setLocation(300,300);
fr.setBackground(Color.lightGray);
pane.add(Label1);

pane.add(Button1);
pane.add(Button2);

fr.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Button1.addActionListener(this);
Button2.addActionListener(this);
fr.pack();
fr.setVisible(true);
}

public void actionPerformed(ActionEvent event)
{
JComponent b = (JComponent)event.getSource();

if(b == Button1)
{
Label1.setText("Button 1 clicked");
System.out.println("You clicked Button 1");
}

else if(b == Button2)
{
Label1.setText("Button 2 clicked");
System.out.println("You clicked Button 2");
}

}
public static void main(String args[])
{
JButtons a = new JButtons();
a.initialize();
}
}


and i called at prompt java test
output is...

You clicked Button 2
You clicked Button 1
You clicked Button 2

[Jean-Sebastien Abella]

and if i commented the system.out in the first file the one that call Runs I don't have any output...